I am interested in a new GC with an O-FID for oxygenates in gasoline. Anyone with pros or cons for certain instruments? Currently I'm using D4815 on HP 5890 and have been since '92, the system is solid, but age is a factor. The dual column installation is a nightmare. 0.53 Guard unioned to a 0.25 TCEP and connected to 0.32 DB-1 analytical via 10 port valve. Backflush set with methylcyclopentane and MTBE. Data acquisition by PE Turbochrom, which was installed recently.
By Hugh Goldsmith on Wednesday, March 8, 2000 - 02:07 pm:
SRI Instruments makes a low cost D4815 system
about $12,000 including the data system. A dual column oven arrangement is a option. This allows the TCEP column to be at a totally different temperature than the DB-1. SRI also makes a Thermionic ionization detector which is selective
to oxygenates. A simple split injection onto a DB-1 followed by the TID detector can speciate the oxygenates for about $8000. including the data system.
By Doug Janson on Thursday, March 16, 2000 - 11:43 am:
The traditional D4815 configuration, when used for gasoline samples, usually does not need a guard column. This simplifies the plumbing quite a bit. I am surprised that you have experienced problems, D4815 is generally a solid configuration with little or no difficulty. The TCEP has historically been the weakest link, but these have improved over the past few years. Concerning the pros and cons, you may consider asking a company that offers both O-FID and FID based analyzers for operating costs, maintenance requirements, etc.:
Wasson-ECE offers D4815 and D5599 (OFID)and several "combined" configurations.
Wasson-ECE, Ft Collins, CO. tel 970 221-9179
AC Analytical Controls also offers standard ASTM configurations and customs.
AC Analytical Controls, Bensalem PA tel 215-638-7078
By Les on Friday, March 17, 2000 - 09:11 am:
The guard is only a meter long and at the injector for on-column injection and to catch any dirt or septa. The plumbing problems occur around the valve. The valve body sits atop the GC and in the heated AUX zone. All the columns join to the 10 p valve via fused silica adapters/port reducers. I use Scotch tape and a light hand to get the columns down before placing the actuator. I'm not having problems with the system, just looking down the road a bit.
The EPA governs what tests are allowed for certification of gasoline. I was under the impression that EPA was going to O-FID and may eliminate D4815 in the near future. I was looking for manufacturers that people have had success with or the mfgs that people have found difficult.
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